| __ | 8. | acute angle | | A. | an angle formed by opposite rays (180o) |
| __ | 9. | adjacent angles | | B. | an angle formed by perpendicular rays (90o) |
| __ | 10. | complementary angles | | C. | an angle between 90o and 180o |
| __ | 11. | congruent angles | | D. | an angle between 0o and 90o |
| __ | 12. | obtuse angle | | E. | angles that share a common ray |
| __ | 13. | right angle | | F. | angles that combine to make a straight angle-sum of 180o |
| __ | 14. | straight angle | | G. | angles that combine to make a right angle-sum of 90o |
| __ | 15. | supplementary angles | | H. | angles that share a common vertex but have opposite rays |
| __ | 16. | vertical angles | | I. | angles with the same size |